Why aren't more of these companies bringing on developers and then developing them into the employees that they want? Is it due to most company cultures not accommodating this sort of thing?
This used to be how every company worked. Manufacturers trainedt people. But companies have pushed the cost of training onto workers. Now there are tons of positions requiring training going unfilled. NPR had a story about this not too long ago.
I think that there is also an issue with training people, then losing them to successful companies that don't have to train people. H1-b visa holders are the obvious exception... Cheaper than Americans. And they need an employer sponsor to stay in the country which makes leaving for another job difficult.
I think training programs that feed into jobs ala hacker school are at least a step in the right direction.
Ultimately, I would like to see companies form coalitions to support training people. I think that that could work. Get some economies of scale combined with attempts at innovation. Have tracks for devops, testing, project management etc. Do research on how to train people. And do it cheaper and better than an academic institution by teaching both concepts and implementation and having certification to industry standards, not academic ones.
When I started at my current position I was pretty good at hacking away at whatever coding task they gave me, but as far as the intricacies of working with a cross functional team of dozens of developers and business people, balancing priorities, coordinating timelines, independently identifying needs, taking initiative, and so forth, I had to learn all that on the job.
To actually respond to your question, though, I think the need for apprentice-style programs is gradually becoming more apparent. The day to day of an average working developer is way different than you might expect from going through a university CS program. Really, on the job training is already happening, the cost is just being absorbed with the first n months of a junior developer starting a job, so it's currently hidden.
Companies that do not have a heavy internal tech focus will be far less inclined to invest in this sort of thing.
Most internships I have seen generally treat the intern as the grunt; no good projects / most of their work can be discarded at the end of their internship.